Base web and protective backing web combination



April 3, 1962 H. J. HOFFMAN 3,023,280

BASE WEB AND PROTECTIVE BACKING wEB COMBINATION Filed Feb. 8, 1960 FRICTION COATING l2 BACKING WEB SToCK SHEET I ADHESIVE BASE wEB RELEASE CoATING 0N BACKING wEB SToCK SHEET FIG. I

FIG. 3

FIG. 6

CREPE SHEET OF BACKING wEB 32 33 INNER FACE SHEET OF BACKING wEB 3| Imummmmmmwm..

ADHESIVE 30 BASE WEB RELEASE COATING ON INNER FAC SHEET OF BACKING wEB E INVENTOR' HARRY J. HOFFMAN BY 7 A5 ZMI/AM ATTORNEYS United States Patent Ofitice 3,Z8,Zdh Patented Apr. 3, 1962 3,028,280 BASE WEB AND PROTECTIVE BACKING WEB COMBINATION Harry J. Hofiman, Monrovia, Calif., assignor to Avery Adhesive Products, Inc, Monrovia, Calif., a corporation of California Filed Feb. 8, 1960, Ser. No. 7,394 1 Claim. (Cl. 154-535) This invention relates to adhesive products such as labels, stickers, tapes, and other similar articles and the web combinations from which such articles are die-cut or otherwise formed. More particularly the invention relates to adhesive products having backings to protect the adhesive surface prior to use.

Backings have been commonly employed to protect the adhesive surfaces of products such as labels, tapes, etc. However one of the problems encountered in the use of these protectors is that while the backing must remain securely in contact with the adhesive surface during manufacture and sale, the backing also must be capable of being easily removed by the consumer at the time that the label or tape is being used.

Many suggestions have been made as to ways of removing protective backings simply and easily. For example, Dreher U.S. Patent No. 2,364,607 is directed to a method in which the center portion of the backing for an adhesive tape is split and the area of adhesive tape under the split is not coated with an adhesive (which otherwise would come through the split). The ungummed portion provides a free edge which can be grasped to remove the protective backing sheet. In another proposal, the backing sheet may be divided into two sections overlapping in the center. In this case, the overlapping non-adhering portion of the outside backing sheet provides a free edge for removal of the first section, and the non-adhering center portion of the other backing sheet acts as a starting point for removal of the second section.

Although these methods make removal of protective backings somewhat easier, the fact that an ungummed starting point must be provided creates additional prob lems. For example, when the top surface of a label having a backing sheet with ungummed areas is printed, there are variations in the printing on the gummed areas as against the ungummed areas. When a label having two overlapping backing sheet sections is printed, there are printing variations between the overlapping and the non-overlapping sections.

The above-discussed shortcomings have been advantageously eliminated by providing embrittled zones in preselected portions of the backing web as described in copending application of Burton D. Morgan, Serial No. 749,837, filed July 21, 1958. However such embrittlement of pro-selected zones involves a predetermination of the areas where separation is to occur at the time of manufacture of the web combination. In many applications this will be desirable. In many other applications it undesirably restricts the variety of possible end uses. According to certain important aspects of the present invention, provision may be made for easy removal of protective backings from then associated adhesive-coated base webs at any one or a number of locations which need not necessarily be pre-selected, but may be randomly selected by the end user.

The invention involves the concept of providing a backing web in association with an adhesive-coated base web with the backing Web being arranged to have a relatively smooth face readily slidable on the adhesive-coated base web and a relatively rough-textured face through which transverse forces may be rnanuaily applied to subject the interface between the base web and the backing web to shearing forces in local areas.

In one advantageous aspect of the invention, these features may be employed to enable corners or edge portions of the combined base web and backing web to be brought slightly out of register in order to provide a starting tab for separation of the Webs.

A particularly advantageous aspect of the invention involves the further concept of providing a web combination as described above in which the backing web is of a flaccid character and is capable of readily buckling outwardly from the adhesive-coated base web at locations adjacent those of the above-mentioned locally obtaining shearing forces between the base web and the backing web. Tabs may be formed and picked up at central areas of the backing web with particular advantage according to this aspect of the invention, as Well as being also advantageously capable of being formed and picked up at edge portions of base-and-backing combinations, if desired. In the latter case particularly, a further advantageous feature is the ready formation of a sizable and conveniently manipulatable graspable edge or tab adjacent edge portions of a web combination, as illustrated and described below.

Other objects and advantages of the invention will be apparent from the foilowing detailed description and drawings, in which:

FIGURE 1 is a schematic cross-section of a web combination embodying the invention.

FIGURE 2 is a view similar to FEGURE l and illustrat ing one typical step in a preliminary portion of the ma.- nipulation of the web combination in order to form a starting tab.

FIGURE 3 is a top View of the showing of FIGURE 2.

FIGURE 4 is a view similar to FIGURE 3 showing a later stage in the manipulation of the Web combination.

IGURE 5 is a view of an alternative successive manipulative stage succeeding that shown in EEGURE 2.

PISURE 6 is a View showing a step optionaiiy succeeding that illustrated in FIGURE 5.

FIGURE 7 shows an alternative web combination which may embody the invention.

Shown in FIGURE 1 is a base web 10 which is coated on at least one side with an adhesive 11 and which is combined with a protective backing web, the backing Web being combined with the base web on the face of the base Web that is coated with the adhesive 11. In this embodiment of the invention, the backing web comprises a backing web stock sheet 12 having a first or inner face in releasable association with the adhesive-coated base web and a second or outer face which is relatively roughtextured as compared to the inner face of the backing web. The outer face of the backing web may be given its rough texture by a friction coating 14 which may comprise any known abrasive material or friction material suitable for this purpose, such as silica, silicon dioxide, talc or the like, supported or carried in a film former such as nitrocellulose, ethyl cellulose, cellulose acetate butyrate, polyvinyl chloride copolymers and the like. Examples of coating composition formulations which result in a coating which will offer a high degree of resistance to sliding of a finger (or pencil eraser or the like) are as follows:

Example 1 Parts by weight Nitrocellulose (RS type /2 sec. viscosity) 100 Silica, sized to a. fine grade (e.g. Syloid 244 of Da- Talc or silicon dioxide of a fine grade is substituted for the silica in the above formulation.

Examples IV through VI Ethyl cellulose is substituted for the nitrocellulose of Examples I-III.

Examples VII through IX Cellulose acetate butyrate is substituted for the nitrocellulose of Examples I-III.

The smooth inner or first face of the backing web is readily slidable on the adhesive-coated base web due to its smoothness. It is of substantial advantage to coat this face with a release coating, the release coating contributing to the smoothness of the inner face or at least not materially derogating therefrom. A number of appropriate release coatings or low-adhesion coatings are known to the art. Examples are coatings in which polyvinyl carbamates comprise the release agent as disclosed in U.S. Patent 2,532,011; those in which acrylic ester copolymers comprise the release agent as shown in U.S. Patent 2,607,711; Gelva resin solutions employing a polyvinyl acetate copolymer as the release agent and commercially available from Shawinigan Resins Corporation; and coatings employing silicone polymer combinations as the release agent as disclosed in copending application of Lester R. Dickard, Serial No. 678,040, filed Augst 14, 1957, now U.S. Patent No. 2,885,554.

FIGURE 2 illustrates the web combination as above described being manipulated by a user preparatory to separation of the base web and the protective backing web. Assuming that pressure is imposed from the thumb (or from a tool such as a pencil eraser) through the rough-textured outer face of the backing web 12 in a direction in FIGURE 2 away from the viewer or toward the corner edge of the combination, the result will be as in the sequence illustrated in FIGURES 3 and 4. FIG- URE 3 illustrates as a top view the initial stage of the manipulation; the same stage as shown in FIGURE 2. FIGURE 4 illustrates a succeeding stage when the backing web has slipped over the side edge of the web combination so that the adjacent edges of the backing web and the base web are out of register. With the webs in this relationship the user can with his other hand grasp the exposed edge of the backing web 12 and readily peel it away from the base web 10. Alternatively he may exaggerate the condition of FIGURE 14 and in some circumstances accomplish a permanent disassociation between the corner portions of the webs 12 and so that enlarged corners starting tabs are provided for immediate or subsequent separation of the two webs.

According to one important concept of the invention, the backing web may be made sufficiently flexible to be capable of readily buckling outwardly from the adhesivecoated base web at locations adjacent those at which localized shearing forces are imposed between the webs. The proper flexibility of the backing web may be arrived at for any particular application and web combination by successively reducing the thickness or other flexibilitygoverning parameters of the backing webs in successive samples until it is observed that the backing web has the characteristic of readily buckling outwardly from the adhesive-coated base web at locations adjacent those on which the localized shearing forces are applied. For example in a commercial application of labels, where backing webs of 40 pound paper (i.e., paper weighing 40 pounds per ream, a ream being 500 sheets, 24 inches by 36inches in dimesion) have been used as protective means for adhesive coatings, it has been found that with the provision of the features of the present invention as previously described and further with the reduction of the backing web to a 28 or 30 pound paper, the ready out- Ward buckling contemplated by this aspect of the invention is achieved.

In the above sense, the backing web may be designated a flaccid web. FIGURE 2 is appropriate for illustrating the manipulation of such a flaccid web, this figure now constituting an illustration of the initial phase of the sequence illustrated sequentially in FIGURES 2, 5 and 6. In this case, the user may impose a transverse pressure on the Web combination by exerting with his thumb a forward pressure, that is, a pressure to the left as illustrated in FIGURE 2. This will result in inboard sliding of the backing web with respect to the base web and concurrent outward buckling of the backing web at a location adjacent that at which localized shearing forces are applied between the webs. This is illustrated in FIGURE 5. In this stage, the outwardly buckled portion 20 of the backing web may be grasped by the user and manipulated as a starting tab to separate the webs. In this connection it will be evident that the manipulation as just described may be performed in a center portion of the web combination rather than adjacent an edge thereof as specifically illustrated. Central manipulation may involve stretching or tearing of the backing web rearwardly or sidewardly of the direction of sliding movement of the backing web relative to the base web.

When the manipulation as just described is performed adjacent an edge portion of the web combination, it is in some applications advantageous to continue the manipulation, as by continuing forward movement of the thumb, causing the buckling portion 20 to continue to grow until the condition of the backing web illustrated in solid lines in FIGURE -6 is reached. At this stage the outer edge of the backing web will in many applications spontaneously spring up slightly as illustrated for example by the edge portion 23 shown in dotted lines. Such a portion forms a convenient and sizable starting tab.

FIGURE 7 illustrates a Web combination which is appropriate to the practice of the invention in all aspects as previously described and which is in some applications particularly applicable to the desirable characteristics of ready stretching and rupture of the backing web. In the combination of FIGURE 7 there is provided a base web 30 which is coated on at least one side with an adhesive 31 and Which is combined with a protective backing web, the backing web being combined with the base Web on the face of the base web that is coated with the adhesive 31. In this embodiment of the invention, the backing web comprises a very thin smooth surfaced paper or sheet 32 to which is permanently adherently laminated a common crepe paper 33. The first or inner face of the backing web comprises the face of the thin inner face sheet 32 which faces the adhesive 31. The rough-textured second or outer face of the backing web comprises the rugose outer surface of the crepe paper 33. The backing Web lamination is highly flexible and the smooth face sheet 32 is very thin having by Way of example a thickness of less than .001 inch and preferably a thickness of about .0005 inch. By combining a crepe and thin paper in this manner, there may be provided a backing which is flaccid within the meaning of this patent application, and which advantageously has considerable body for ease of handling. The first or inner face of the backing web, that 3 is, the face of the inner face sheet 32 which is in facing relationship to the adhesive 31, is advantageously provided with a release coating as indicated in FIGURE 7 and as previously described in connection with the example of FIGURE 1. i

It will be apparent that additional variants may be employed in the practice of the invention Without departing from the inventive concepts taught in this description.

What is claimed is:

An article of manufacture comprising a base web, an adhesive coating on one side of said Web, a protective backing Web combined with said base Web on said adhesive-coated side thereof, said backing Web having a first face in releasable association with said adhesive-coated base Web and a second face constituting an outer face of said article of manufacture, said second face being relatively rough-textured and said first face being relatively smooth and readily slidable on said adhesive-coated base web under shearing loads imposed by transverse forces frictionally applied through said second face, said backing Web comprising a lamination of a smooth surfaced paper and a crepe paper, said smooth surfaced paper being of a thickness of less than .001" and forming said first face of said backing web, and said crepe paper constituting said second face of said backing web.

References Cited in the file of this patent UNITED STATES PATENTS 

